The present invention relates to a data transmission arrangement, utilizing a statistic coding, the arrangement comprising a transmitting section intended for the transmission of data provided in the form of a digital sample series and at least one receiving section. The transmitting section includes a statistic encoding member for converting the digital samples into statistic codewords and a multiplexing circuit for inserting synchronizing words between the statistic codewords. Each receiving section is provided with a receiving member for receiving the transmitted codewords, and a correction circuit cooperating with a synchronizing word detection circuit to enable the recovery of the digital sample series after processing by a statistic decoding member so as to apply them to a user member.
Such an arrangement is used with great advantage in, more specifically, the transmission, in digital form, of television images, wherein each sample series then represents one picture line and the samples represent the picture elements (pixels).
The problem encountered in this type of arrangement is that it is sensitive to transmission errors. A transmission error affects in the first place the sample containing this error and may have repercussions on the subsequent samples. The result would be that, although the samples will ultimately be recovered appropriately, they no longer correspond to the position of the sample in the sequence. This change in place is propagated from line to line and thus an image of a highly degraded quality is obtained. The use of a synchronizing code renders it possible to solve this problem.
In the French Patent Application no. 8709446 filed by Applicants on Jul. 3rd, 1987, to which U.S. Pat. No. 4,876,698 corresponds, it is proposed to distribute the synchronizing code over the packets. Although this measure is highly satisfactory as regards the errors still existing in packets, that is to say during a period of time exceeding the transmission period of a synchronizing codeword, Applicants have nevertheless looked for a solution which requires less material and ultimately renders, in actual practice, the arrangement appropriately insensitive to errors.